The present invention relates to a new and improved reverse osmosis filtration purification system for drinking water intended primarily for home use. More particularly, it relates to a new and improved reverse osmosis filtration purification system incorporating a three way faucet dispense assembly and a low pressure blow-molded storage tank assembly employing tap water at line pressure as the drive fluid for dispensing purified R.O. water at line pressure to the point of use.
Many different kinds of reverse osmosis drinking water purification systems are known and commercially available. The systems have been developed for use in the home and are generally configured to be installed within an under sink compartment in the kitchen. A separate pure water dispensing faucet outlet is provided next to the regular tap water faucet of kitchen sink.
The reverse osmosis systems rely primarily on a reverse osmosis membrane filter to remove dissolved solids from incoming tap water to improve the purity of the water. Reverse osmosis systems work best at removing divalent ions from the water which may provide an unpleasant taste or cause undesirable scaling. For example, R.O. filtration purified water having lower dissolved solids content is particularly desired for drinking water, for watering plants, as a purified water feed for ice makers and to provide reduced salt containing waters for irons, humidifiers and other appliances susceptible to scaling. Moreover, in addition to the reverse osmosis membrane filter modules, other filter modules are commercially available such as granular activated carbon as well as more specialized filter modules for removing specific impurities such as iron and nitrates as well as sediments and even microbes. These additional filters may be connected in series with the R.O. filter module to provide a desired level of product water purity. These additional filters are useful for removing chlorine and other halides which impart an unpleasant taste to drinking water.
The reverse osmosis filter receives impure tap water at line pressure. The R.O. membrane divides the incoming tap water stream into a stream of purified R.O. water, containing reduced dissolved solids content and a stream of concentrate or waste water having a higher level of dissolved solids. In a conventional R.O. system, the purified water is directed to a storage container for collection and for dispensing to a point of use faucet.
In the past, specialized storage tanks capable of withstanding significantly elevated pressures were employed as the storage tanks for an R.O. system. Early storage tank embodiments included an inflatable bladder defining a pure water chamber into which pure water exiting from the R.O. system was directed. The remainder of the inner space of the high pressure tank containers could be filled with a drive fluid such as compressed air. As incoming purified water gradually filled the inflatable bladder within the storage container, the compressed air was pressurized to higher and higher pressure. Thereafter, when the dispensing faucet was opened to withdraw pure water from the storage tank, the high pressure of the compressed air in the tank would drive the pure water out of the storage tank. A major problem with these compressed air drive fluid storage tanks is that, as a significant quantity of purified water is withdrawn from inside the bladder, the pushing pressure of the compressed air against the bladder gradually decreases. This results in low pressure flow at the faucet as the tank is emptied, often only an annoying trickle. An illustrative example of a compressed air storage tank assembly for an R.O. system as shown in U.S. Pat. No. 3,719,593.
A system which describes using incoming tap water as a drive fluid for driving out the purified water from the storage tank is described in U.S. Pat. No. 3,794,172. In accordance with that system, a pressure container for the storage tank is used. In addition, a specialized diaphragm valve is connected to incoming tap water and the dispenser faucet. The high pressure storage tank and the diaphragm valve are relative expensive components that unnecessarily increase the expense of the overall system. Moreover, the diaphragm valve includes a plurality of input connections that are required to be made which increases the possibility for system leakage which is undesirable.
Still another R.O. filtration purification system is described in U.S. Pat. No. 4,021,343. This system employs the concentrate or waste water exiting from an R.O. filter module as the drive fluid for pushing against a bladder provided in a high pressure storage tank in order to dispense purified R.O. water at elevated pressure through a point of use faucet. This system employs an expensive high pressure container and elaborate valves with multiple connections to the R.O. unit. Utilizing the waste water from reverse osmosis filter as a dry fluid has the advantage that when the pure water spigot is turned on, a rush of incoming tap water tends to flush impurities through the reverse osmosis membrane. These systems work well in applications wherein the reverse osmosis membrane is intended for long term relatively permanent use.
More recently, there have been developed considerably less expensive reverse osmosis filter modules which are intended to be disposable. Accordingly, the need to purge impurities from the membrane is no longer as important since the disposable R.O. filters have limited use lives and are intended to be exchanged with new filters on a regular schedule. In view of the development of disposable R.O. filter modules, it is also desired to decrease the overall cost of manufacturing and using on under sink reverse osmosis filtration purification system making these purified water systems more accessible to a larger number of homes and other end use contexts such as in vending machines.
Accordingly, to overcome the shortcomings of the prior art devices, it is an object of the present invention to provide a new and improved reverse osmosis filter purification system for drinking water which is less expensive to make, install and use.
It is another object of the present invention to provide an R.O. purifier system which delivers purified R.O. water to a point of use faucet at substantially line pressure.
It is a further object of the present invention to provide an R.O. filtration purification system capable of employing an inexpensive low pressure container for storing R.O. water and for delivering same to a point of use faucet on demand.
It is still another object of the present invention to provide a new and improved R.O. filtration purification system including a minimum of connections between subassemblies and components to minimize the risk of leakage.